Presentation Modulation of picosecond dynamics of troponin by a cardiomyopathy-causing mutation studied by quasielastic neutron scattering

松尾, 龍人  ,  Matsuo, Tatushito  ,  富永, 大輝  ,  河野, 史明  ,  柴田, 薫  ,  藤原, 悟

Troponin (Tn) is a protein consisting of three subunits (TnC, TnI, and TnT) and plays a central role in the regulation of cardiac muscle contraction in a Ca2+-dependent manner. Various mutations of human cardiac Tn are known to cause familial hypertrophic cardiomyopathy due to aberration of the regulatory function. In this study, we investigated the effects of one of these mutations, K247R of TnT, on the picosecond dynamics of the Tn core domain (Tn-CD), consisting of TnC, TnI and TnT2 (183-288 residues of TnT), by carrying out the quasielastic neutron scattering measurements on the reconstituted Tn-CD containing either the wild-type TnT2 (wtTn-CD) or the mutant TnT2 (mtTn-CD) in the absence and presence of Ca2+. It was found that the mutation decreases the residence time of atomic motions in the absence of Ca2+. Changes in dynamics in response to Ca2+-binding are also different between the wtTn-CD and mtTn-CD. In particular, the mtTn-CD exhibits a larger amplitude than the wtTn-CD in the presence of Ca2+, suggesting that the conformational degree of freedom is larger for the mtTn-CD than for the wtTn-CD. This increased flexibility of the mtTn-CD would cause the functional aberration reported for the K247R mutation.
1st QST International Symposium: “Quantum Life Science”

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